A mobile communication system has evolved to provide various high-speed large-capacity services to mobile stations (MSs). Examples of the mobile communication system include a high speed downlink packet access (HSDPA) mobile communication system, a high speed uplink packet access (HSUPA) mobile communication system, a long-term evolution (LTE) mobile communication system, a LTE-advanced (LTE-A) mobile communication system, a high rate packet data (HRPD) mobile communication system proposed in a 3rd generation project partnership 2 (3GPP2), and an institute of electrical and electronics engineers (IEEE) 802.16m mobile communication system.
Generally, in a mobile communication system, a handover procedure is performed if an MS moves. If the handover procedure is performed, a context for the MS is forwarded from a serving base station (BS) to a target BS, the target BS provides continuously a service to the MS based on the context for the MS which has been forwarded from the serving BS. The context is classified into a static context and a dynamic context, each of the static context and the dynamic context will be described.
Firstly, the static context includes total configuration information related to the MS, capability information, service flow & quality of service (QoS) information, etc. and does not change although the handover procedure is performed.
Secondly, the dynamic context indicates information which is exchanged between BSs for status information synchronization for the MS, and includes counter information, timer information, state machines status information, data buffer contents, etc.
If data which the MS should receive is buffering on a buffer of a serving BS, the data which the serving BS is buffering is forwarded to a target BS while the MS performs a handover procedure.
For convenience, ‘data which an MS should receive’ will be called as ‘MS receiving schedule data’. Thereafter, if the MS finally accesses the target BS according to completion of the handover procedure, the target BS starts to transmit the forwarded MS receiving schedule data to the MS.
In an LTE mobile communication system as a typical mobile communication system, if a handover procedure of an MS starts to perform, a serving BS forwards MS receiving data which is forwarded through a packet data network (PDN) gateway to a target BS through a link which is established with the target BS. In this data forwarding method, while a network signaling is ongoing, the MS may resume receiving data although the MS accesses the target BS on a state on which a path between the target BS and the PDN gateway is not yet established.
Recently, a cooperative communication system in which a plurality of BSs provide a service to an MS by cooperating with one another, that is, the plurality of BSs provide the service to the MS using a multiple BS cooperation scheme has been proposed, and a study for the cooperative communication system has progressed.
The same handover procedure may occur in the cooperative communication system, so it is important for a total system performance of the cooperative communication system that the cooperative communication system continuously provides a service to the MS.
However, the cooperative communication system has been recently proposed and a study for the cooperative communication system has been actively progressed, so a data scheduling process according to performing a handover procedure has not been concretely proposed.
So, there is a need for data scheduling scheme which is appropriate to a situation of the cooperative communication system, i.e., a communication situation on which a multiple BS cooperation scheme is used and in which normal data transmission/reception is possible.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.